Life Sciences Lesson 1 & 2
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Transcript of Life Sciences Lesson 1 & 2
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Animal Nutrition
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Introduction
Plants are autotrophic and thus theyproduce
their own food.
Without the process so called photosynthesis,
plants can not produce their own food.
This process takes place in chlorophyll
containing plants.
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Primary Producers (autotrophs)
These plants can make
their own food using
Sunlight
Chlorophyll
Water
Carbon dioxide
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Introduction
This is in contrast with heterotrophs
They must obtain their food from other
organisms.
Most heterotrophic organisms have to convert
solid, complex food into soluble state which is
capable of being absorbed into the blood and
transported to all the cells of the body.
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What determines our diet?
Our diet is determined by:
Fashion fashion dictates what we eat as well aswhat we dress in.
Religions different world religions give guidanceon what can or should be eaten. E.g. Pork
Doctor prescription / recommendations.
Moral grounds objections to the killing ofanimals.
Personal health choices.
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Why do we need to eat??
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Carbohydrates and Fats
We need carbohydrates to:Supply energy to the body.
Provide energy (calories)
Lipids (Fats and Oils)
They are Insoluble in water
They Provide HIGH ENERGYLipids provide over twice carbohydrates
energy.
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Proteins
They help in:Growth and repairs of all cells
Development from young to adult
Production of hormones, enzymes and antibodies
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Minerals
In maintaining body process we needvitamins and mineral salts.
They help us in:
Bone development
Teeth development
Chemical process regulation
Nervous system function and also in
Reproduction
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Food
Type
Carbohydrate
Fat
Protein
Sugars
These are types of food that we normallyconsume.But what happens to the food we eat??
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There are 6 main steps that food
travels in animals digestive system.
1. Ingestion:
2. Digestion3. Absorption
4. Translocation
5. Assimilation
6. Egestion
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Ingestion
It is the Process of takingfood into the body.
We take in food through
the mouth; we chew thefood to form a bolus.
The bolus is swallowed
and moved by peristalsis.
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Peristalsis
It is a wave like
muscle that
contracts to pushfood down the
esophagus and the
small intestine
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Digestion begins in the mouth
Mechanical digestion
It is the process of
breaking down foodphysically.
Food is then convertedmechanically and
chemically fromcomplex to simple statein bolus form.
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Mechanical digestion
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Digestion
Fig. 41.16
Peristalsis (rhythmic contractions) carries the bolusto the stomach
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absorption
Nutrients are absorbed as monomers by the cellslining the gut.
Translocation/ transport
the blood transports the nutrients to all the
parts of the body.
Assimilation
Nutrients are removed from the blood by the
cells by diffusion and active transport, to buildsubstances like proteins for nuclear material andcell membranes and also to replace damagedcells and organelles.
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Egestion
Undigested food is passed out of the body, by
a process called defecation
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Summary
Ingestion
Egestion
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Lifestyle and energy relationships
Please refer to module 1 unit 2
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Energy Pyramids
Only about10% of energypassed onbetweentrophic levels
Few Carnivores
More Herbivores
All supported
by energyfromproducers
Most is lostthrough theorganismslivingprocesses
F d Ch i
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Phytoplankton
Zooplankton
Fish
Shark
Label the trophic levels as herbivore, carnivore, producer,top predator. Indicate which are consumers.
Top Predator
Carnivore
Herbivore
Producer
ConsumersFood Chain
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Lifestyle of herbivores
They have much competition for food so they
developed different feeding habits.
Some are grazers and they feed on grass
E.g. Cow, sheep,....
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Herbivore lifestyle
Browsers eat foliage from trees and shrubs
Examples will be animals like elephants and
giraffes.
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Type of food
Plants foliage
Roots
Underground stems Seeds
And fruits
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Type of teeth
They have well developed molars andpremolars to grind plant matter well.
Jaws can be moved sideways to enable
grinding process.
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Stomach
More than 1 stomach to digest cellulose.
Mutualistic bacteria produce their enzyme
cellulase for digestion of the cellulose in
plants.
Eg. Cow has four chambers or so called
stomach
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Energy relationship
Primary consumers; must consume large
amounts of plant material to meet their
energy requirements.
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Carnivores lifestyle
They are commonly predator and scavengers.
Predators hunt for prey, catch them and then eat
them.
Examples will be lions, snake, spider,
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Scavengers
They feed on dead bodies.
Once the predator have eaten their fill,
scavengers will eat the remainders or the
carcass.
Examples: vultures, hyenas, vultures,
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Type of food
Flesh of other animals
Blood
And bones
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Type of teeth
Well developed canines to rip flesh.
Have carnassials teeth to crush and chew
bones
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Carnivore Teeth Adaptation
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Stomach
Well developed stomach with gastric juice
that enables the digestion of proteins and
bones.
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Energy relationship
Secondary consumers feed on primary
consumers
They require less volume of food because
their diet is rich in proteins.
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Omnivores lifestyle
They feed on plants and animals
Eg: we as human beings, feed on plants
and animals.
In some cases omnivores are predators andhunt for prey.
Omnivores generally live in group and
share their food Why?
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Omnivore
Eats a mixture of plants andanimals e.g. Pigs, humans
Increased chance of survivalas they are not restricted toone diet.
In some cases omnivores arepredators and hunt for prey.
Omnivores generally live ingroup and share their food
Why?
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Type of food
Plant leaves
Vegetables
Fruits
Nuts
Eggs
And meat
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Type of teeth Teeth help in (mechanical
breakdown) of food. Teeth are similar shape and
size, incisors, canines,premolars and molars
Incisors are used forcutting.
Canines are used forpiercing and holding.
Molars have large surfacearea and are used forgrinding.
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Stomach
They have well-developed stomach with
gastric juice to digest proteins and fats.
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Energy relationship
Tertiary consumers; consume least amount of
food as their diet is rich in all the nutrients
that their body need.
Especially proteins.
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Omnivore
Eats a mixture of plants
and animals
E.g. Pigs, humans
Increased chance of
survival as they are not
restricted to one diet.
Digestive Systems are Adapted to their
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Vertebrate dentition generally matches the diet
Digestive Systems are Adapted to theirOwners Lifestyles
Fig. 41.26
An adult human has 32 teeth:
Incisors for cutting
Canines for tearing
Premolars and molars for crushing and'grinding
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Summary of previous lesson
1. Humans, like most animals, are HETEROTROPHS; Weeat other organisms for Food and Energy.
2. FOOD CONTAINS NUTRIENTS, OR MOLECULES THATPROVIDE ENERGY AND MATERIAL FOR GROWTH ANDREPAIR.
3. NUTRIENTS ARE CHEMICAL SUBSTANCES NEEDED BYTHE BODY FOR GROWTH, REPAIR, ANDMAINTENANCE.
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Summary of previous lesson
4. All the different FOODS in the world CONTAIN at least ONE
ofSIX KINDS OF NUTRIENTS: CARBOHYDRATES, PROTEINS,
LIPIDS (FATS), VITAMINS, MINERALS AND WATER.
5. FOUR of these Nutrients- Carbohydrates, Proteins, Fats, and
Vitamins-are ORGANIC COMPOUNDS Because they contain
the Elements Carbon, Hydrogen, and Oxygen.
6. The TWO Remaining Nutrients-Minerals and Water-are
INORGANIC COMPOUNDS
Fig. 5-8
C ll lCell walls
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Glucose
monomer
Cellulosemolecules
Microfibril
Cellulosemicrofibrilsin a plantcell wall
0.5 m
10 m
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Enzymes that digest starch by hydrolyzing linkages cant hydrolyze linkages in cellulose
Cellulose in human food passes through the
digestive tract as insoluble fiber
Some microbes use enzymes to digest cellulose
Many herbivores, from cows to termites, have
symbiotic relationships with these microbes
Copyright 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings
Fig. 5-9
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Mechanical and Chemical
digestion
Mr. Khoza
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Introduction
Digestion can be divided into 2 processes:
mechanical and chemical breakdown of the
'insoluble, complex molecules that can be
absorbed.
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Mechanical process
This process physically breaks the food to
increase the surface area for enzyme action.
Enzymes are proteins that catalyze (i.e.,
increase the rates of) chemical reactions.
it also serves to move and mix the food.
http://en.wikipedia.org/wiki/Proteinhttp://en.wikipedia.org/wiki/Catalysishttp://en.wikipedia.org/wiki/Reaction_ratehttp://en.wikipedia.org/wiki/Chemical_reactionhttp://en.wikipedia.org/wiki/Chemical_reactionhttp://en.wikipedia.org/wiki/Reaction_ratehttp://en.wikipedia.org/wiki/Catalysishttp://en.wikipedia.org/wiki/Protein -
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The mechanical process involves:
Chewing of food (mastication)
Bolus formation which involves saliva andtongue
Peristalsis where muscle action moves thefood along the alimentary canal (tube).
The churning movement of the stomach to
mix the chyme (food + enzymes) Segmentation in the small intestine to mix the
chyme and move it along the canal.
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Roughage
Is very important to the mechanical process.
It help to:
Speed up the movement of food in the digestive
tract (area).Stimulate peristalsis in the colon.
Decrease the occurrence of haemorrhoids andconstipation
Absorb water and makes the contents bulky(large)
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Chemical process
Enzymes break complex nutrients down into
their monomer state (simple molecules) so
that absorption into the blood can take place.
Compounds are hydrolysed as follows:
Carbohydrates- glucose, fructose and
galactose.
Proteins amino acids
Lipids fatty acids and gycerol
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Chemical process
Digestive juices like hydrochloric acid (in the
stomach)and bile (produced by the liver) help
the enzymes to function optimally.
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The Digestive System
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The Digestive System
Mouth
Oesophagus (peristalysis)
Stomach
Small Intestine (jejenum)
Liver
Large Intestine
Gall Bladder
Pancreas
Rectum
Anus
Lets find out what happened to your breakfast today!
(Breaking food down into smaller pieces)
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Oesophagus
Approximately 25cm
long
Moves food from the
throat to the stomach
Muscle movement called
peristalsis
If acid from the stomachgets in here thats
heartburn.
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Stomach
Stores the food you eat
Chemically breaks it
down into tiny pieces Mixes food with
digestive juices
Acid chyme -(pH 2,8) inthe stomach kills
bacteria
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Small Intestine
Small intestines areroughly 6 metres long.
Enzymes and bile are
added. Villi increase the surface
area to help absorbtion.
Nutrients from the foodpass into the bloodstreamthrough the smallintestine walls.
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Liver
Directly affectsdigestion byproducing bile Bile is an enzyme that
helps dissolve fat Processes nutrients in
the blood, filters outtoxins and waste.
Is often called thebodys energy factory
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Gall Bladder
Stores bile from
the liver
Delivers bile whenfood is digested
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Pancreas
Producescompounds to
digest fats and
proteins Neutralizes acids
that enter small
intestine Regulates blood
sugar by producing
insulin
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Large Intestine
About 1.5 metres long
Accepts what smallintestines dont absorb.
Absorbs water andminerals from the wastematter.
Absorption meanstaking into the body viathe blood stream.
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Rectum and Anus
Rectum
About 15cm long
Stores wastebefore egestion.
Anus
Muscular ring that
controls egestion.
Write the name of each
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Write the name of each
colored organ:
Green:
Red:
Pink:
Brown:
Purple:
Green:
Yellow:
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Answers
Green: Oesophagus
Red: Stomach
Pink: Small Intestine
Brown: Large
Intestine
Purple: Liver
Green: Gall Bladder
Yellow: Pancreas
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Humans have 4 types of teeth:
Incisors to cut thefood
Canines to tear the
foodPremolars to grind
and crush the food
Molars to grind andcrush the food.
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Teeth
Mammals have two sets of teeth:Milk teeth in children (22 teeth)
Permanent teeth in adults (32 teeth).
The process of chewing the food is called
mastication.
In humans, the dental formula is calculated on
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half of the jaw, left or right side of the mouth.
The formula is:
2 . 1 . 2 . 3--------left jaw
2 . 1 . 2 . 3---------right jaw
Human(adult)
I -2/2 C -1/1 P 2/2 M 3/3 = 16 X 2 = 32
This indicates: 2 Incisors, 1 Canine,2 Premolars
and 3 Molars on 1 side the top jaw and thesame for the bottom jaw.